The accumulation of excess heat is a major constraint in the design of thermal inkjet printheads capable of high speed printing. The printheads have semiconductive silicon chips in which a large number of heaters are embedded elements in the chips. The heaters are selectively driven with electric current to vaporize water in the inkjet ink and thereby expel drops of ink by the force of such vapor action. As the number and speed of repetition of such operations is increased, removal of excess heat from the printhead becomes a major design objective.
This invention removes excess heat by attaching the chip to a radiator body using a thermally conductive adhesive. However, electrical leads of an electrical circuit tape (commonly known as a TAB circuit, for tape automated bonding) are also connected to the chip. Since a thermally conductive adhesive is typically electrically conductive to a significant extent, the TAB leads are first undercoated along their entire length with an insulative material.